Pleural Effusions - Lecture notes 1 PDF

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Lecture notes by Dr. Afreen Naaz of Aligarh Muslim University....

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PLEURAL EFFUSIONS DEFINITION • Abnormal accumulation of fluid between parietal pleura and visceral pleura is called pleural effusion. Accumulation of purulent fluid is called empyema. Normally, the pleural space contains a small amount of fluid (about 0.26 ± 0.1 mL/ kg) which allows the lungs to inflate and deflate with minimal friction. • A minimum of 500 mL of fluid is necessary for clinical detection of pleural effusion. • Transudate is an ultrafiltrate of plasma, resulting from increased hydrostatic pressure or decreased serum oncotic pressure. This is essentially an effusion with normal pleura. Transudative effusions are also called hydrothorax although some use this term for any pleural effusion. • Exudate resembles plasma and is rich in proteins. This results from increased capillary permeability. This is essentially an effusion with diseased pleura.

CLASSIFICATION AND CAUSES • Transudates Congestive heart failure, cirrhosis of liver, nephrotic syndrome, severe malnutrition, peri-toneal dialysis, hypothyroidism, constrictive pericarditis, Meigs' syndrome (benign ovarian tumours with ascites and pleural effusion • Exudates Tuberculosis, malignancy, pneumonia, pulmonary infarction, rheumatoid arthritis, pancreatitis, systemic lupus erythematosus, drug-induced effusion, benign asbestos-related effusion, Dressler's syndrome, intra-abdominal abscess, Meigs' syndrome (can be transudative as well), ruptured amoebic liver abscess, chylous pleural effusion

CLINICAL FEATURES • Symptoms and signs of pleurisy may precede the development of pleural effusion. • Breathlessness may occur, the severity of which is related to the size and rate of accumulation of fluid. PHYSICAL FINDINGS IN THE CHEST • Inspection and palpation will disclose shift of trachea and mediastinum (shift of apex beat) to the opposite side, reduction in the chest movements on the affected side, bulging of the intercostal spaces, fullness of the affected chest and markedly reduced vocal fremitus. Measurements reveal diminished chest expansion, increase in the size of the affected hemithorax and an increase in spinoscapular distance. • Percussion reveals a stony dull note over the fluid. Upper level of the dullness is highest laterally in the axilla, and is lower anteriorly and posteriorly (Ellis-S-shaped curve). A small pleural effusion on the left side may be detectable only by the obliteration ofTraube's space on percussion. Likewise, a small effusion on the right side may be detectable only by tidal percussion.

• On auscultation, intensity of the breath sounds is markedly diminished-to-absent over the fluiq. Adventitious sounds are not audible. Vocal resonance is markedly diminished over the fluid.

INVESTIGATIONS Chest Radiograph • Chest radiograph (posteroanterior view) in the erect posture can detect pleural effusion. A minimum of 200 mL of fluid is required for detection in this view. Radiological Features of Pleural Effusion in an Erect Chest Film

• Mediastinal shift to the opposite side • Obliteration of costophrenic angle • A dense uniform opacity in the lower and lateral part of hemithorax • Upper border of the opacity is concave upwards and is highest laterally • Wider than normal interlobar fissure in "interlobar effusion" • Encysted interlobar effusion may be seen as a rounded opacity resembling solitary pulmonary nodule (phantom tumour) • Encysted effusion in the presence of adhesions between contiguous pleural surfaces (loculated effusion) • Shift of mediastinum towards the side of effusion in a patient with massive effusion indicates either an endobronchial obstruction or a mediastinum encasement by tumour (e.g. mesothelioma) Ultrasonography • Can detect as little as 5 mL of effusion. • It is useful in differentiating loculated pleural effusion from pleural tumour or pleural thickening. • It detects septations within pleural fluid with greater sensitivity than CT scanning. • Useful in localisation of an effusion prior to aspiration and biopsy. • Detection of solid pleural abnormalities may suggest pleural malignancy. Pleural Aspiration and Fluid Analysis

Light's Criteria • Light's criteria are used to differentiate exudative from transudative fluid. These include one or more of the following: • Ratio of pleural fluid protein to serum protein level >0.5 • Ratio of pleural fluid LOH to serum LOH >0.6 • Pleural fluid LOH level >2/3rd of the upper level of serum LOH levels • These criteria are highly sensitive for identifying exudative fluid but have lower specificity, i.e. some patients with transudative effusion will be classified as exudative fluid using this criteria. Therefore, if clinical findings suggest a transudative effusion but the pleural fluid appears to be an exudate on Light's criteria, the difference between the albumin level in serum and pleural fluid should be measured. Almost all patients with transudative effusion have a serum albumin level that is more than 1.2 g/dL higher than the pleural fluid albumin level (serum-effusion albumin gradient). • Of note, a large percentage of exudates will be misclassified if serum-effusion albumin gradient is used as the only method of differentiating between transudates and exudates. Causes of Lymphocytic Pleural Effusions • Malignancy (primary or secondary) • Tuberculosis • Lymphoma • Congestive heart failure (long standing) • Rheumatoid effusion • Chylothorax • Uraemic pleuritis Pleural Biopsy • Usually indicated in some exudates that are undiagnosed. • Closed pleural biopsy can be performed with Abrams or Cope or Tm-cut needle. It should be done under ultrasound guidance when the effusion is small or loculated. • The needle should be inserted through an intercostal space at the area of maximum dullness on percussion and at the site of maximum radiological opacity or at a site determined by ultrasonography. Other Investigations in Pleural Effusion • Pleural fluid tumour markers like carcinoembryonic antigen (CEA), cancer antigen 125 (CA-125), cancer antigen 15-3 (CA 15-3) and cytokeratin 19 fragments (CYFRA) do not have any role in routine investigations of pleural effusion. However, immunocytochemical markers (e.g. epithelial membrane antigen, CEA, calretinin, etc.) can be performed on the atypical cells seen in the effusion. • Blood examination for total and differential leucocyte counts, ESR, proteins, sugar, LDH, amylase, rheumatoid factor and antinuclear factor. • Sputum examination for tubercle bacilli and malignant cells. • Mantoux test.

• In a massive effusion, a repeat radiograph after removal of a large volume of fluid may reveal an underlying parenchymal lesion. • CT scan of chest. • Biopsy or fine needle aspiration of scalene lymph nodes. • Bronchoscopy and biopsy. • Thoracoscopy (video-assisted or open surgical) and biopsy.

MANAGEMENT OF PLEURAL EFFUSION • Treatment of the underlying causes. • Therapeutic aspiration may be necessary to relieve dyspnoea. Not more than 1 L should be removed at a sitting because pulmonary oedema (refer below) may follow removal of large volumes. • Insertion of chest tube if rapid reaccumulation of fluid occurs. • Pleurodesis for malignant effusion using bleomycin or talc powder....